The present invention relates to thread winding apparatuses for winding threads around objects.
Fiber reinforced plastic (FRP) is formed by reinforcing plastic with reinforced fiber material. The reinforced fiber material improves the heat resistance, strength, rigidity, and anti-crack properties of plastic. The FRP is thus provided with improved performance and is generally used for various objectives. Various methods are known for forming an FRP product. Particularly, a filament winding method is widely used in forming, for example, pressure tanks or pipes. The method maintains a reinforced fiber thread in an integral state without cutting the thread, thus maximizing the strength of the fiber thread.
FIG. 7 shows an example of an apparatus for forming an FRP product in accordance with such a filament winding method. A cylindrical mandrel 101 is rotationally supported by, for example, a frame (not shown). Linear guide members 102 and a ball screw 103 are adjacent to and parallel to the mandrel 101. A traverse 104 is secured to the linear guide members 102 and slides along the linear guide members 102. The traverse 104 includes a thread guide 105. A threaded hole 107 extends through the traverse 104 and engages the ball screw 103. When the ball screw 103 is rotated by a moving device (not shown), the traverse 104 slides along the linear guide members 102. A reinforced fiber thread 106 is passed through the thread guide 105 and wound on a surface of the mandrel 101 through the thread guide 105. A desired winding pattern is obtained by controlling the rotating speed of the mandrel 101 and the speed of the traverse 104.
The reinforced fiber thread 106 is formed of, for example, glass fiber, carbon fiber, or aramid fiber. The fiber is selected in accordance with the use and shape of an FRP product. A single product may include a reinforced fiber thread 106 formed of one material. Alternatively, the product may include a plurality of reinforced fiber threads 106 formed of different materials. For example, FRP forming a compressed-natural-gas tank includes glass fiber and carbon fiber. That is, an outer fiber layer is formed by the glass fiber, and an inner fiber layer is formed by the carbon fiber. If the tank is dropped, for example, the glass fiber in the outer layer, which is relatively fragile, is fractured to absorb the shock. However, the carbon fiber in the inner layer, which is relatively hard, prevents the tank from being ruptured. The contents of the tank therefore does not escape.
However, to form an FRP product including a plurality of reinforced fiber threads 106 formed of different materials, the operation of the thread winding apparatus must be discontinued for switching the reinforced fiber threads 106. That is, when winding of one reinforced fiber thread 106 is completed, the thread 106 must be removed from the thread guide 105. Subsequently, another reinforced fiber thread 106 of a different material is passed through the thread guide 105 before being wound around the mandrel 101. This lowers efficiency and increases costs.
Accordingly, it is an objective of the present invention to provide a thread winding apparatus with an improved operational efficiency that quickly replaces a reinforced fiber thread when forming an FRP product using a plurality of reinforced fiber threads of different materials.
To achieve the above objective, the present invention is a thread winding apparatus for winding a thread around an object while rotating the object. The apparatus includes a plurality of guide members for selectively guiding a plurality of threads to a surface of the object. One guide member corresponds to one thread, and the guide members move along the object. A moving device moves the guide members.
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.